The other reason is that maintaining a server and its services is sometimes a full-time job :/
The server kept running out of memory and shutting down MySQL so my sites stopped working. I started to learn how to read logs and saw that there is a huge amount of malicious activity directed at my server all the time.
Yesterday I installed Fail2ban which meant installing postfix. I got it working (took most of the day) but I can't send emails to my gmail account because I need to set up dkim and dmarc and other stuff. I have a list. But first I have to learn how to do all this stuff.
I use Fedora every day at work but I'm obviously no sysadmin and you are so right. All this takes hours and hours to learn and then to stay on top of it. When I was on shared hosting I had a lot less control and options but it was a lot easier as well.
Why do you need dkim or dmarc to send to gmail? If you send a test php mail does gmail pick it up?
gmail-smtp-in.l.google.com[173.194.207.27] said: 550-5.7.1 This message does not have authentication information or fails to pass 550-5.7.1 authentication checks. To best protect our users from spam, the 550-5.7.1 message has been blocked. Please visit 550-5.7.1 https://support.google.com/mail/answer/81126#authentication for more 550 5.7.1 information. d203si1756652qkb.228 - gsmtp (in reply to end of DATA command)
there are tons of guides on troubleshooting mysql resource issues. Are they great? I don't know. Have I tried what is mentioned in many of them? Yes. I still have issues. I don't think it's just mysql though. I think it is a lot of little things that I'm slowly eliminating one by one.
http://digitaloceanvps.blogspot.com/2014/04/best-configurati...
For gmail interesting.. wonder why google trusts me.